The pulmonary system provides homeostasis and repair of the lung in response to attack by pathogens, toxins, pollutants, and other types of injuries.
Asthma is a non-infectious chronic inflammatory disease of the respiratory system characterized by a reversible airways obstruction. Acute airway obstruction, bronchial hyper-responsiveness and inflammatory state of the bronchial mucosa with increased levels of inflammatory mediators, are the most evident phenomenon which characterizes this pathology. Despite the increase in the prescribed anti-asthmatic treatments, the current trends indicate asthma is set to be the most chronic disease in industrialized countries, affecting mostly the children (10%) than the adults (15%).
Chronic obstructive pulmonary disease (COPD) is the most common of all the respiratory disorders in the world, which embraces several inflammatory pathologies that often co-exist. The WHO predicts COPD will become the third most common cause of death world over by 2020 accounting 8.4 million lives. Although asthma for the last 25 years has been managed therapeutically, with a combined bronchodilator and anti-inflammatory therapies, in contrast to this COPD have no effective treatments currently, while the efficacy of the corticosteroids is controversial. Hence, there is an urgent need to develop novel anti-inflammatory drugs having both the bronchodilatory and anti-inflammatory activity, having applicability to treat both COPD as well as asthma. Thus, the development of therapies for bronchial asthma has become the major focus of the pharmaceutical industry in the field of respiratory disorders.
Airway stem cells have been implicated in the pathology and progression of chronic airway diseases and yet also hold the promise of physiological and ultimately therapeutic repair of damage wrought by these conditions. Chronic airway disease is often regiospecific with allergic rhinitis affecting the sinuses, asthma, cystic fibrosis, and bronchiolitis obliterans in the large conducting tubes such as the bronchi and bronchioles, and COPD, pulmonary fibrosis, and pulmonary hypertension affecting the distal regions of the airways involved in oxygen exchange. A major focus of airway pathology therefore is to understand if and how stem cells initiate repair programs, participate in airway epithelial remodeling seen in chronic conditions, and mechanisms underlying defects in repair as in pulmonary fibrosis.